Vent stops are used to restrict the opening of windows and doors, and are primarily used on double hung windows and sliding doors where a sliding sash window or door member slides from a first position to a second position. The vent stop prevents the sash from moving past a selected point, but generally permits the window to be opened a certain amount for ventilation or other purposes. For example, a window vent stop may permit a sash window to be opened four or five inches to allow air circulation, which only constitutes a portion of the window's normal travel stroke in moving from a fully closed position to a full open position. One of the considerations leading to the use of such vent stops is security concerns relating to unauthorized entry from unlocked and otherwise unprotected doors and windows.
Such door and window vent stops are typically adapted to permit installation through an opening into a hollow area of a sash member or window frame, where it is retained therein using a top plate and flexible mounting clips, such as the mounting clips 14 shown by U.S. Pat. No. 5,575,116 to Carlson for a “Window Vent Stop.” Such clips are limiting in that they are not functional for a window that does not have a hollow frame, which may include new wood windows, and also many older windows already in service in building, into which a stop may be desirably installed.
The vent stop of the current invention incorporates unique retention means which permit it to be installed into windows that do not have hollow frames, and thus permit retrofit installation of the stop into older windows, and particularly wood windows.